The present disclosure relates to a sewing machine capable of embroidering including a thread trimming mechanism to execute a thread trim operation based on a thread trim instruction and a thread wiping mechanism to execute a thread wiping operation of an upper thread trimmed by the thread trimming mechanism.
Sewing machines capable of embroidering include a cloth presser to press work cloth when carrying out an embroidery sewing process, a cloth presser mechanism to drive the cloth presser, a thread trimming mechanism to trim an upper and lower thread on sewing completion and a thread wiping mechanism to wipe the trimmed upper thread with a wiper member.
For example, JP-A-2003-103080 discloses a multi-headed industrial sewing machine including a thread trimming device provided in the sewing machine bed to automatically trim the upper thread and the lower thread and a thread wiping device provided on a head of the sewing machine which, after thread trimming by the thread trimming device, pulls out an upper thread end connected to an eye of a sewing needle by lifting the upper thread above the needle plate.
The aforementioned thread wiping device includes a wiper having a hook on the end, a wiper drive mechanism to drive the wiper to wipe the thread and an upper thread retainer to retain the upper thread end of the wiped thread after sewing is completed. When a thread trim operation is executed by a thread trimming device when a needle bar and a cloth presser is in a lifted position, the wiper, after being projected to the projecting position, is immediately returned to the original retracted position. Consequently, the trimmed upper thread is hooked by the hook of the wiper, pulled out of the work cloth and retained by the upper thread retainer provided above the needle plate.
Since an industrial sewing machine has plenty space between the bed and the head, a relatively large thread wiping device can be provided on the wiper device allowing for a provision of an upper thread retainer. However, in a household sewing machine, the machine itself is small, hence only a small space is available between the bed and the head, which requires a size reduction of the wiper device and an omission of the upper thread retainer.
However, the omission of the upper thread retainer gives rise to cases, in which the trimmed and wiped upper thread hangs from the wiper down to the cloth presser. If the work cloth is moved to the next sewing position in such state, in cases the direction of movement of the work cloth is the same as the thread wiping direction and the like, the upper thread end could slip in under the cloth presser depending on the direction of movement. As a result, the upper thread end could be pressed by the cloth presser, lowered to start the sewing process and sewn into subsequent sewing sequence.
On the other hand, the wiper mechanism of the sewing machine disclosed in JP-B-H06-52782 includes a wiper body rotatably supported by a sewing machine frame, a presser foot to press a work piece to be sewn, a vertically moving unit to be vertically moved with the presser foot, and a connecting link having one end contacting the upper end of the vertically moving unit, and the other end connecting to the wiper body. In this wiper mechanism, the wiping of the sewing thread is actuated by lifting the presser of the sewing machine, which in turn lifts the vertically moving unit contacting the presser. Then, the lifting of the vertically moving unit moves the lower end of the wiper body towards the sewing needle via the connection link to wipe up the sewing thread.
However since the wiper body moves in conjunction with the vertical movement of the presser foot, a stroke of the movement of the wiper body cannot be increased. Therefore, in some cases the trimmed upper thread cannot be reliably pulled out from the work cloth. Also, similar to the thread trimming device described in the above separate patent publication, even if the upper thread could be pulled out from the work cloth, there is a possibility that the upper thread end gets pressed down by the presser foot and sewn into subsequent sewing sequence, when the upper thread is hanging from the wiper body to the presser foot at sewing start time, as in the thread wiping device disclosed in the above-noted JP-A-2003-103080.